Docker: create deployment for DReSA

[nrmay]

Create Docker files for DReSA deployment:

• build
  • DReSA (ruby on rails application)
  • unicorn
  • nginx
  • postgresql
  • redis
  • sidekiq
  • solr
  • sendmail
  • cron
  • backups (production)
  • etc.
• compose for deployments
  • Development
  • Production
  • CircleCI ?
• document tasks
  • deployment
  • maintenance